As wind and solar generation displace traditional synchronous power plants, power systems face a growing vulnerability: the loss of natural inertia that historically dampened frequency swings. Converter-interfaced renewable sources lack this inherent stabilizing property, making grid operators dependent on active-power reserves from wind and PV facilities to arrest frequency decline during disturbances.
Researchers have developed an adaptive primary frequency regulation (PFR) strategy specifically designed for wind–photovoltaic renewable stations operating in low-inertia conditions. The approach, called RCR-PFR, maps real-time frequency measurements and their rate of change into a risk index that quantifies the severity of an ongoing frequency event. Simultaneously, the controller calculates an executable-reserve credibility index by evaluating available power headroom, resource variability, feasible ramp rates, and saturation margins. This dual assessment allows the controller to dispatch wind and solar support only when operationally feasible, avoiding unrealistic commands that cannot be physically delivered.
A key innovation is the integration of a battery energy storage system (BESS) that acts as a backstop, compensating only for support requests that wind and PV cannot meet. This strategy prevents over-reliance on batteries while ensuring that critical frequency support is always available.
Simulation results from a standard load-step disturbance showed the frequency nadir (lowest point) improved to 49.788 Hz, a 0.132 Hz gain compared to conventional approaches. Under more severe conditions with constrained reserves and low equivalent inertia, the BESS compensation reduced unmet support energy from 1.23 MWh to 0.011 MWh and eliminated extended low-frequency periods that threaten grid stability.
While simulation results are promising, the developers note that field validation, multi-machine transient studies, and hardware-in-the-loop testing are necessary before practical deployment at power stations. The work represents a meaningful step toward operating reliable grids with majority-renewable generation.
